IEC 60747-5-5:2020(E) specifies the terminology, essential ratings, characteristics, safety tests, as well as the measuring methods for photocouplers. Note: The term "optocoupler" can also be used instead of "photocoupler". This edition includes the following significant technical changes with respect to the previous edition: a) optional data sheet basic insulation rating in accordance with IEC 60664-1:2007, 6.1.3.5; b) editorial corrections on the use of VIORM; c) editorial corrections on Figure 2: Time intervals for method b); d) addition of an alternative surge pulse VIOSM test method.